This invention relates generally to friction clutches used in vehicles and more particularly to clutch brakes utilized in non-synchronized heavy-duty transmissions. Such brakes are activated upon disengagement of a main clutch to retard rotation of transmission gearing for easier gear shifting.
It is well known in the art to retard vehicle transmission gears prior to gear shifting by using a clutch brake activated by the throw-out mechanism which disengages the main clutch. Torque limiting clutch brakes which provide a limited amount of braking torque are also well known, and are widely preferred because of their durability and long life.
Resilient means have been used in torque limiting clutch brakes to cushion the braking effect and to prevent excessive braking pressure which may damage the clutch brake. For example, prior art devices have included opposed Belleville springs for establishing a predetermined frictional load between the inner and outer members of clutch brakes. Clutches utilizing opposed Belleville springs must be carefully designed and accurately assembled in order that one spring balances the other. An imbalance between the springs can cause one to overcome the other, reversing its concavity and interfering with the operation of and shortening the life of the clutch brake.